Skull kettlebell



FIG. 1 is a perspective view of a skull kettlebell according to our new design;

FIG. 2 is a front view thereof;

FIG. 3 is a rear view thereof;

FIG. 4 is right side view thereof;

FIG. 5 is left side view thereof;

FIG. 6 is a top view thereof; and,

FIG. 7 is a bottom view thereof.

The broken lines illustrate portions of the skull kettlebell which form no part of the claimed design. 

CLAIM The ornamental design for a skull kettlebell, as shown and described. 